Iron

Question 1

what two processes is iron involved in in the body?

Answer 1

oxygen transport 
electron transport (production of ATP)

Question 2

where is the majority of body iron found?

Answer 2

in haem

Question 3

what is haem made of?

Answer 3

porphyrin ring and iron

Question 4

where does iron absorption occur?

Answer 4

mainly in the duodenum

Question 5

what dietary factors can enhance iron absorption?

Answer 5

haem iron
ascorbic acid
alcohol

Question 6

why is haem iron more readily absorbed?

Answer 6

it has its own dedicated transporter

Question 7

what effect does ascorbic acid have on iron?

Answer 7

reduces it to its Fe2+ form - ready to be absorbed

Question 8

what dietary factors can inhibit iron absorption?

Answer 8

tannins found in tea
phytates in things like cereal, nuts and seeds
calcium

Question 9

what enzyme prepares iron for absorption and how?

Answer 9

duodenal cytochrome B

reduces ferric iron to ferrous iron

Question 10

what transporter transports iron into the enterocytes?

Answer 10

DMT-1

aka divalent metal transporter 1

Question 11

what protein facilitates iron export from the enterocyte?

Answer 11

ferroportin

Question 12

what protein regulates iron absorption?

Answer 12

hepcidin

Question 13

what is the major negative regulator of iron uptake?

Answer 13

hepcidin

Question 14

what causes increased production of hepcidin by the liver?

Answer 14

increased iron load

inflammation

Question 15

how does hepcidin regulate iron absorption?

Answer 15

binds to and degrades ferroportin

this traps iron in duodenal cells and macrophages

Question 16

what happens to hepcidin levels when iron deficient?

Answer 16

decrease

Question 17

what test can be done to assess functional iron status?

Answer 17

haemoglobin concentration

Question 18

what test can be done to assess transport iron status?

Answer 18

% saturation of transferrin

Question 19

what test can be done to assess storage iron status?

Answer 19

serum ferritin

tissue biopsy - rarely needed

Question 20

what does transferrin do?

Answer 20

transports iron from donor tissue to tissues expressing transferrin receptors

Question 21

what are the iron “donor tissues”?

Answer 21

macrophages
intestinal cells
hepatocytes

Question 22

what should transferrin saturation be in normal iron levels?

Answer 22

20-50%

Question 23

what happens to transferrin saturation in iron overload?

Answer 23

elevated

Question 24

what happens to transferrin saturation in iron deficiency?

Answer 24

reduced

Question 25

what is the key iron storage protein?

Answer 25

ferritin